The present invention relates to a drive control method and apparatus for a sheet processing machine which processes a sheet.
Conventionally, as a sheet processing machine of this type, a sheet-fed rotary printing press comprising a printing press main body (sheet processing device) and feed device (sheet supply device) is known as described in, e.g., reference 1 (Japanese Utility Model Laid-Open No. 62-26344) and reference 2 (Japanese Patent Laid-Open No. 9-255183). A plurality of conveyor tapes which extend on a feeder board and convey paper (sheet), a feedboard on which the conveyed sheet travels smoothly, a register device which is located at the distal end of the feedboard and aligns the registration of the sheet in the circumferential direction and lateral direction, and a swing arm shaft pregripper which supplies the registered sheet to the printing press main body are arranged between the feed device and printing press main body of the sheet-fed rotary printing press.
FIGS. 23 and 24 show the side structure and perspective structure of the feed convey unit of a sheet-fed rotary printing press described in reference 1. FIG. 23 shows a feed device (feeder) 101 and printing press main body 102. As the printing press main body 102, only one of a plurality of printing units is shown.
The feed device 101 comprises a pile board 104 on which sheets 103 are stacked and which is lifted as the sheets 103 are fed to reduce its weight, a suction device (not shown) which grips the sheets (stacked sheets) 103 on the pile board 104 one by one from the upper layer and sends them to a portion between a pair of upper and lower feed rollers 105 and 106, and the like. Each printing unit of the printing press main body 102 comprises a plate cylinder 107 with a plate mounted on its surface, a blanket cylinder 108 in contact with the plate cylinder 107, and an impression cylinder 109 which is in contact with the blanket cylinder 108 and applies a printing pressure to the sheet 103 passing between the blanket cylinder 108 and impression cylinder 109. A transfer cylinder 110 is arranged between the impression cylinders 109 of adjacent printing units to transfer the sheet 103 between them.
A feeder board 111 extends between the feed rollers 105 and 106 and the front end of the printing press main body 102 to be inclined slightly. A pair of front and rear rollers 112 and 113 which are pivotally, axially supported are disposed near the front and rear ends of the feeder board 111. A plurality of conveyor tapes 114 extend between the rollers 112 and 113 to line up in the widthwise direction of the feeder board 111 such that their upper traveling portions are in contact with the feeder board 111.
A small frame 115 (FIG. 24) which supports the rollers 112 and 113 and feeder board 111 is fixed to the printing press main body 102. A feedboard 116 with almost the same width as that of the feeder board 111 extends in front (downstream in the convey direction) of the small frame 115 at a predetermined gap from the front end of the small frame 115 to be inclined at an angle of inclination almost the same as that of the feeder board 111. A circumferential direction register device comprising a front lay 117 and the like is arranged at the front end of the feedboard 116. A swing arm shaft pregripper 118 grips the sheet 103 that has stopped as it abuts against the front lay 117, and swings to gripping-change the sheet 103 to the gripper of the impression cylinder 109.
A stay 119 is disposed between the small frame 115 and feedboard 116 with its two ends being fixed by a pair of left and right frames 120. A side lay device 121 which aligns the registration in the circumferential direction of the sheet 103 under conveyance is mounted on each of the two ends of each frame 120 such that the side lay device 121 can movable and adjustable in the widthwise direction of the feeder board 111. One convey plate 123 which constitutes a convey table together with the stay 119, and a plurality of convey plates 124 line up on the stay 119 in the widthwise direction of the feeder board 111.
In this sheet-fed rotary printing press, the suction device grips the sheets 103 stacked on the pile board 104 one by one and feeds them forward. The feed rollers 105 and 106 which rotate in contact with each other vertically capture the sheet 103 and feed it onto the conveyor tapes 114, and the conveyor tapes 114 convey the sheet 103. The conveyed sheet 103 is released from the conveyor tapes 114 at the position of the roller 112, is supplied onto the feedboard 116 and smoothly travels on the feedboard 116, and abuts against the front lay 117 to stop there. At this time, the sheet 103 is registered in the circumferential direction by the front lay 117 and in the lateral direction by the side lay devices 121. The swing arm shaft pregripper 118 grips the sheet 103 that has been registered in the circumferential direction and lateral direction. After that, the swing arm shaft pregripper 118 gripping-changes the sheet 103 to the gripper of the impression cylinder 109, and the sheet 103 is printed while being conveyed.
In this sheet-fed rotary printing press, when transferring the sheet 103 from, e.g., the suction device to the feed rollers 105 and 106 and from the feed rollers 105 and 106 to the conveyor tapes 114, slippage may occur between the sheet 103 and the feed rollers 105 and 106 and between the sheet 103 and the conveyor tapes 114, so that the timing to transfer the sheet 103 to the swing arm shaft pregripper 118 may shift accordingly. If this change in timing increases, printing cannot be performed at the correct position on the sheet 103, causing defective printing. In view of this, rotary phase adjustment is performed. That is, the rotary phase of the feed device 101 with respect to that of the printing press main body 102 is adjusted, so that the timing to transfer the sheet 103 to the swing arm shaft pregripper 118 is set at an appropriate timing.
In the conventional sheet-fed rotary printing press, as shown in FIG. 25, the feed device 101 is connected to the printing press main body 102 through a clutch 125, and a prime motor 126 of the printing press main body 102 drives the feed device 101. Hence, if the timing to transfer the sheet 103 to the swing arm shaft pregripper 118 changes during printing, the printing press must be stopped temporarily, the clutch 125 must be “disconnected”, and the operator must adjust the rotary phase of the feed device 101 manually. After the adjustment, whether or not the rotary phase is adjusted correctly cannot be checked unless “connecting” the clutch 125 to drive the printing press and feeding the sheet 103. Hence, adjustment must be repeated a number of times to impose the load to the operator. Also, the adjustment takes time to degrade the operation efficiency. Also, unwanted waste paper is generated (first problem).
The amount of slippage described above which occurs when transferring the sheet 103 changes depending on the printing conditions such as the speed of the printing press (speed of final printing), the size, thickness, and quality of the sheet 103, and the like. Every time the printing conditions are changed, the operator must adjust the rotary phase of the feed device 101 manually, thus causing a problem (second problem) similar to the first problem.
In the example described above, the rotary phase of the feed device with respect to the rotary phase of the printing press main body is adjusted. The same problems also arise when adjusting the rotary phase of the printing press with respect to the rotary phase of the feed device.
In the example described above, the feed device employs the conveyor tapes. The same problems also arise in a roll type feed device, as described in reference 3 (Japanese Utility Model Laid-Open No. 3-23138), which does not employ conveyor tapes. In the roll type feed device, a sheet is fed to a portion between a feed roller and feed roll, and is conveyed on a feedboard by rotational driving of the feed roller. In this case, slippage occurs only when supplying the sheet from a suction device to the portion between the feed roller and feed roll.